Current textile technology uses a number of approaches to impart fire resistance or flame retarding ability to fibers and fabrics. In one method, flame retardant chemical finishes are applied directly to the substrate; suitable chemicals include illustratively tris(2,3-dibromopropyl) phosphate, ammonia-cured tetrakis(hydroxymethyl)phosphonium hydroxide (THPOH), tetrakis(hydroxymethyl)phosphonium chloride (THPC), decabromodiphenyloxide (DBDPO), and various halogen/phosphorus, nitrogen/phosphorus, boron/phosphorus and antimony compounds and certain inorganic salts. In another method, chemicals are added directly to fiber spinning solutions to obtain flame retardant fibers, exemplary trade names of which are "Acrylon Plus", and "Zefron FR" acrylic fibers and "Trevira" polyesters. In yet another method, fibers are produced which are intrinsically flame retardant; examples are aramids such as "Nomex" and "Kevlar", modacrylics such as "Verel", "SEF" and "Orlon FR" and polybenzimidazole (PBI).
U.S. Pat. No. 4,572,862 (Ellis) discloses inter alia a composition suitable for use as a fire barrier when cured, which comprises a flowable, substantially uniform dispersion of (A) a binder component comprising a powdered, substantially uniform mixture of (1) heat activated MgO, and (2) high alumina calcium aluminate cement comprising 70% to 80% Al.sub.2 O.sub.3 ; in (B) a gauging component in about a stoichiometric amount sufficient to react with the binder component, and comprising an aqueous solution of MgCl.sub.2 or MgSO.sub.4, wherein the aqueous solution has a specific gravity of about 26.degree. to about 32.degree. Baume. The entire disclosure of U.S. Pat. No. 4,572,862 is incorporated herein by reference.
The composition described in the foregoing paragraph may, as described in the Ellis Patent, be coated on a solid substrate, and the latter may be adhered to a rigid support so as to constitute a fire barrier. The substrate may be, by way of example, a non-woven spunbonded polyester fabric or a woven or non-woven fiberglass fabric. The composition of the Ellis Patent is generally described therein as a paint, and the principal applications of the composition lie in the building industry; thus, for example, it is mentioned that multilayers may be built up from paint impregnated non-woven spunbound polyester geotextile fabric, so as to form structural laminates. The purpose of the fabrics utilized in this Patent appear to be to provide stress-relief foci and to form a basis or perhaps a reinforcement for structural purposes.
"Pyrotite" is the trade name of product marketed by the Pyrotite Corporation of Miami, Fla., which utilizes the fire-barrier composition disclosed in the Ellis Patent. Certain forms of "Pyrotite" may contain various proportions of latex, in order to impart different degrees of flexibility to the ultimate cured product.
In the Ellis Patent, textile fabrics are used to make structural laminates, but there is no teaching therein that fabrics when coated with the fire-barrier producing composition can be used for the applications for which fabrics are more generally used, such as textiles which need to be subjected to folding or even to a certain amount of crushing, and to which additionally, it is desired to impart fire-retardant properties.
Consistent with the restricted teaching in the Ellis Patent in relation to the employment of fabrics for making e.g. structural laminates, the present inventor has found that, for example, "Pyrotite" compositions, even when containing added latex, do not possess adequate adhesion and flexibility to make their use viable for textile applications. By contrast, the inventor has found that such compositions can be applied to textiles by making a composite laminate employing layers of adhesive and a sealing layer, in addition to an inorganic-based fire-retardant layer. This is to be regarded as a surprising result, since to the inventor's knowledge this kind of lamination has not been used hitherto in order to impart fire-retardancy to textiles, in which the product is flexible in that it is foldable and crushable, at least to some degree, without delamination.